A new treatment appears hopeful for the most severe form of brain cancer, glioblastoma. Monitoring these antiangiogenic therapies mechanistically would greatly aid our understanding of how they might best be used in patients, and recent data suggest that measurement of brain perfusion with MRI using gadolinium-based approaches could be very useful, particularly as an imaging biomarker. However, no single methodology for acquisition or analysis has been tested in at variable field strengths or across vendor platforms. We propose to develop acquisition and analysis methods that will be compatible across field strengths and vendor platforms and quantify the differences in acquisition and analysis. We will first study volunteers to understand the on-site manufacturer and field strength variability. We will then study patients with newly diagnosed glioblastoma who are undergoing treatment with anti-angiogenic agents. It is expected that such an approach will improve the reliability of perfusion MRI as a potential imaging biomarker, and pave the way for a large-scale, multi-center trial that could standardize the implementation of perfusion MRI in measuring tumor response to anti-angiogenic therapies.